About 159 people are believed to have died from swine flu in Mexico, where it originated. Scientists remain confused why the virus seems more fatal there, but also caution that deaths elsewhere are still likely. (Source: CNN)

SHELF DESTRUCTING: Swine flu may not have spread to Antarctica yet, but the continent has still had a rough month. First came news on April 5 that a major ice bridge had ruptured, and now scientists say a chunk of ice nearly the size of New York City has broken off into icebergs from the Wilkins Ice Shelf. Both events are widely blamed on global warming — the Wilkins Shelf has already shrunk by about a third from its size when first discovered decades ago, and temperatures on the Antarctic Peninsula have risen by up to 5.4 ºF in the past 100 years. The ice shelf's crumbling underscored warnings trumpeting from Norway on Tuesday, as Al Gore joined foreign ministers and climate experts from around the world to discuss the dangers posed by melting glaciers and polar ice. (Sources: Reuters, BBC News, MSNBC)

UNEXPECTED SPECTER: Now that Sen. Arlen Specter has switched parties from the Republicans to the Democrats, what does that mean for the climate-change legislation percolating through Congress? Probably not much, explains Grist's Kate Sheppard. While Specter was always a mavericky moderate — sacrificing his political future as a Republican, for example, by approving President Obama's stimulus bill earlier this year — he has made it clear he won't be "a party-line voter any more for the Democrats than I have been for the Republicans," spelling out that he won't be an automatic 60th vote in the Senate. He acknowledges the reality of global warming, but doesn't have a stellar record voting for progressive climate bills. Still, the party switch is motivating some grassroots organizations to lobby extra hard for Specter's vote on upcoming attempts to regulate greenhouse gas emissions. (Sources: Washington Post, Grist)

ENDANGERED SPECIES RULE: The Obama administration continued whittling away at its predecessor's environmental legacy Tuesday, as Interior Secretary Ken Salazar and Commerce Secretary Gary Locke announced that federal agencies will once again be bound by the Endangered Species Act. While they technically already are, a last-minute regulation from the Bush administration allowed agencies to determine on their own whether a project would threaten a protected species, without the need of consulting scientists. Obama had previously asked Salazar to review the rule, and Salazar announced Tuesday that "by rolling back this 11th hour regulation, we are ensuring that threatened and endangered species continue to receive the full protection of the law." (Source: Washington Post)

AIR APPARENT: Despite tougher air-quality laws and a growing focus on environmental health, 60 percent of Americans live in areas with unhealthy air pollution levels. The American Lung Association issued its annual list of the most polluted U.S. cities today, finding that nearly every major city endures unhealthy air quality at times. Los Angeles took the No. 1 spot for the 10th year running for ozone pollution, and Bakersfield, Calif., topped the list for year-round particle pollution. Pittsburgh was the worst city for short-term particle pollution. (Sources: Associated Press, ALA)

GREASING THE WHEELS: As the recession continues pounding away at China's economy, government leaders are responding by relaxing industrial regulations "to help enterprises pass the winter," the L.A. Times reports today. While that's making it easier for businesses, it could be disastrous for workers' rights and the environment. China is already the No. 1 emitter of greenhouse gases and a voracious consumer of carbon-heavy coal, and observers around the world are hoping the country will make some economic concessions at this December's U.N. climate summit to help slow the march of climate change. (Source: L.A. Times)

TRAY NOT BIEN: Colleges and universities around the country are ditching the cafeteria tray, the N.Y. Times reports, in hopes of conserving water, wasting less food, saving money and improving ambience. Nearly half of the 300 institutions with the largest endowments have cut back on tray use in various ways, such as removing them from certain dining halls or holding events like "Trayless Tuesdays." (Source: N.Y. Times)

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